Wheel and/or axle load measuring plates are known to the art, which utilize one or more strain gauges, which can be associated with appropriate circuitry responding to the distortion of the measuring plate for signalling, indicating, recording or registering the wheel or axle load. Additionally, wheel scales which utilize strain gauge sensors fixed to deflectable load cells are known. However, the specific configuration of the load cells utilized in prior art scales, the placement of the load cells in the housing structures of these scales, and the cooperation of the active and inactive elements of these prior art wheel scale devices often yield complex and bulky wheel scales, which are inaccurate and unrepeatable under many conditions of use.
In one known wheel load indicator of this kind, the webs are formed between circular enlargements of a pair of recesses, and strain gauges are adhered to the opposed walls of these enlargements, i.e., to the two opposed web walls. The recesses themselves are closed.
In another known wheel load indicator, the recesses forming a web between them are of slot-like design starting from the lateral edges of the plate. The strain gauges are adhered to the webs in the plane of the upper surface of the plate. With such an arrangement nothing, but bending stresses of a plate loaded by a wheel can be determined.
U.S. Pat. No. 4,098,365 issued Jul. 4, 1978 to L Pietzsch for “Device for the Measurement of Wheel or Axle Loads of Road vehicles” provided a device for measuring the wheel or axle load of a road vehicle. The device comprised a plate supported along its periphery at selected points or by knife edges in a frame. At least two pairs of wire strain gauges were provided along two imaginary lines of the plate, and which were spaced apart by a distance greater than the length of a contact zone of a wheel on the plate. Each pair of wire strain gauges included a wire strain gauge extending in the direction of displacement of the wheel, i.e. perpendicular to the imaginary lines, and a wire strain gauge parallel thereto.
U.S. Pat. No. 4,333,543 issued Jun. 8, 1982 to L Pietzsch for “Wheel or Axle Load Measuring Device for Road Vehicles” provided a measuring plate with at least one strain gauge. A wheel of a vehicle could rest on that plate to generate a signal, which was used to indicate or register the wheel load or axle load of the road vehicle. The measuring plate was received in a frame and had edges, which extended transversely of the direction of vehicle travel. Those edges were bevelled or partly cut away so as to be overhung by complementarily shaped sides of the frame. Those edges were also provided with elastic bars or ribs along the bottom of the plate. The elastic bars or ribs rested upon and supported the center of the plate above a support plate or body, which was disposed below the measuring plate.
U.S. Pat. No. 4,616,723 issued Oct. 14, 1986 to Ing Ludwig Pietzsch GmbH & Co for “Wheel Load Indicator” provided a wheel load indicator, which comprised a rectangular flat plate of a light material having measuring properties. A series of recesses forming webs were provided along two lateral edges of the plate. Strain gauges were adhesively bonded to walls of bores in the area of the webs to determine the shearing stress under the load of a wheel which has been driven on the bending portion.
U.S. Pat. No. 4,775,018 issued Oct. 4, 1988 to W. P. Kroll et al for “Load Cell Assembly” provided a sealed shear load cell assembly for direct mounting to the load transfer portion of the weighing platform of a scale assembly. The load cell assembly cooperated with the weighing platform to provide a structural load-bearing component for the scale assembly. The top surface section of the beam load cell structure provided a predetermined shear segment in the beam structure. A pair of axially aligned, opposing circular apertures were provided to form stress isolation webs along the longitudinal axis of the beam structure. That structure included parallel end walls, which were spaced apart and which were oppositely and vertically centered adjacent the predetermined shear segment in the beam structure. Strain gauges were mounted to each parallel end wall of the stress isolation webs, and bearings were operative on the beam structure at predetermined locations outside each said stress isolation web. An interiorly disposed channel structure was further provided in the beam structure for housing the electrical communicative wiring of the strain gauges. The channel structure further included a centrally disposed aperture extending through the lateral sides of the beam, an aperture through each stress isolation web, and a longitudinally extending channel extending from one of each pair of the opposing circular apertures to the centrally disposed aperture. A sealing material in the interiorly disposed channel structure was further provided for isolating and protecting the electrical communicative wiring from environmental interaction.
U.S. Pat. No. 4,848,493 issued Jul. 18, 1989 to R. W. Hitchcock for “Load Sensing Structure for Weighing Apparatus” provided a load sensing structure for a weighing scale deck, which included two or more low profile flexure members, each of which was shaped like the letter “E”, with two outer legs secured to the deck and the inner leg to the platform. The inner leg had twice the bending strength and stiffness of the two outer legs. All legs had their ends connected in cantilever fashion, either to a common base or to one or the other of the deck and platform. Strain gauges on one leg provided complementary inputs to a bridge circuit under weight loads, but tend to cancel their effects on the bridge circuit under other load conditions.
The present invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest sense and more specific forms will then be further described and defined, in each of the individual claims, which conclude this specification.